Abstract

Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials,number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest the free electrons and heavy particles have different temperatures. In this paper, we present a generalized algorithm for equilibrating the heavy-particle and electrontemperatures and a third user-specified independent thermodynamic variable in a two-temperature plasma mixture. Test calculations based on the equilibration of total pressure vs. electronpressure are presented for three different mixtures.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344. We are grateful to Bill Cabot, John Castor, C. H. Chang, Jeff Greenough, Rob Managan, Phil Sterne, Heather Whitley, Mark Ulitsky, and George Zimmerman for many helpful discussions, and to C. H. Chang for calling our attention to Refs. 3 and 4. This paper is dedicated to the memory of Charles W. Cranfill (April 24, 1945–April 15, 2013).